EP1572769B1 - Method for producing aqueous dispersions - Google Patents

Abstract

The present invention relates to a process for preparing aqueous dispersions. The invention also relates to the formation of core-shell particles in aqueous dispersions. The core-shell particles are useful as impact-modifiers for poly(meth)acrylate moulding compositions.

Description

The present invention relates to processes for the preparation of aqueous dispersions. In particular, it relates to processes for the preparation of core-shell particles in aqueous dispersion; which can be used for toughening of poly (meth) acrylate molding compositions.

It has long been known that the impact strength of molding compositions, in particular of poly (meth) acrylate molding compositions, can be improved by adding a suitable amount of so-called impact modifiers to the molding composition. Here, the use of core-shell particles and / or core-shell-shell particles has prevailed in the art. These generally have an elastomeric phase, wherein in a core-shell structure usually the core and in a core-shell-shell structure usually represent the grafted onto the core first shell the elastomeric phase.

For example, this discloses US Pat. No. 3,793,402 impact-resistant molding compositions, in particular poly (meth) acrylate-based, which 90 to 4 wt .-% of a multistage core-shell particles having a hard core, an elastomeric first shell and a hard second shell. Typical major constituents of the core and the second shell are alkyl methacrylates having 1 to 4 carbon atoms in the alkyl radical, in particular methyl methacrylate. The first shell is composed essentially of butadiene, substituted butadienes and / or alkyl acrylates having 1 to 8 carbon atoms in the alkyl radical. However, it may also contain 0 to 49.9% by weight, especially 0.5 to 30% by weight of copolymerizable monomer units, such as copolymerizable monoethylenically unsaturated monomer units. It is according to US 3,793,402 the presence of 10 to 25 wt .-% of copolymerizable monoethylenically unsaturated monomer units, in particular of styrene, very particularly advantageous.

The total diameter of the core-shell particles is in the range of 100 to 300 nm.

The preparation of the core-shell particles is carried out by multi-stage emulsion polymerization, wherein thermal initiators, such as persulfates or redox-initiator systems are used. The polymerization should be carried out at a temperature in the range of 0 to 125 ° C, in particular in the range of 30 to 95 ° C.

1. A) einen harten Kern aus einem vernetzten Homo- oder Copolymerisat von ethylenisch-ungesättigten, radikalisch polymerisierbaren Monomeren;
2. B) einer in Gegenwart des Kernmaterials erzeugten Elastomerphase mit einer Glasübergangstemperatur nicht über 10 °C, die aufgebaut ist aus
   1. a) einem Alkylester der Acrylsäure mit 1 bis 8 Kohlenstoffatomen im Alkylrest;
   2. b) wenigstens einem vernetzenden Comonomeren mit zwei oder mehr polymerisierbaren Doppelbindungen im Molekül;
   3. c) Arylalkylacrylat oder -methacrylat;
   4. d) einer in Gegenwart der Elastomerphase erzeugten Hartphase aus einem Homo- oder Copolymerisat von ethylenisch-ungesättigten, radikalisch polymeriserbaren Monomeren mit einer Glasübergangstemperatur von wenigstens 50 °C.

Similarly, the German patent application DE 41 21 652 A1 Impact modifier for thermoplastic materials, such as polymethyl methacrylate, consisting of an at least three-phase emulsion polymer containing

1. A) a hard core of a crosslinked homo- or copolymer of ethylenically unsaturated, radically polymerizable monomers;
2. B) an elastomeric phase produced in the presence of the core material having a glass transition temperature not exceeding 10 ° C, which is composed of
   1. a) an alkyl ester of acrylic acid having 1 to 8 carbon atoms in the alkyl radical;
   2. b) at least one crosslinking comonomer having two or more polymerizable double bonds in the molecule;
   3. c) arylalkyl acrylate or methacrylate;
   4. d) a hard phase produced in the presence of the elastomer phase from a homo- or copolymer of ethylenically unsaturated, free-radically polymerizable monomers having a glass transition temperature of at least 50 ° C.

An exemplary examplarily given in this document molding compound (Example 3) has an Izod impact strength at room temperature of 6.2 kJ / m ² , at -10 ° C of 4.7 kJ / m ² and at -20 ° C of 3.7 kJ / m ² . The Vicat softening temperature of the molding compound is 97 ° C.

The preparation of the core-shell particles is likewise carried out by means of multistage emulsion polymerization, alkali metal or ammonium peroxodisulfate being used as initiator and the polymerization being carried out at a temperature in the range from 20 to 100 ° C., for example at 50 ° C.

The German patent application DE 41 36 993 A1 discloses impact-modified molding compositions containing 10 to 96% by weight of a polymer based on polymethyl methacrylate and 4 to 90% by weight of a multistage core-shell-shell particle, wherein for the preparation of the core and the second shell, respectively a monomer mixture is used, which contains substantially methyl methacrylate. The monomer mixture for the first shell comprises 60 to 89.99% by weight of alkyl acrylates having 1 to 20 carbon atoms in the alkyl radical and / or cycloalkyl acrylates having 5 to 8 carbon atoms in the cycloalkyl radical and 10 to 39.99% by weight of phenyl acrylate with 1 to 4 carbon atoms in the alkyl radical and optionally further constituents. The average particle diameter of the core-shell-shell particles is in the range of 50 to 1000 nm, in particular in the range of 150 to 400 nm.

According to this document, the core-shell particles are obtained by a multistage seed latex process in which ammonium or alkyl peroxodisulfates, such as potassium peroxodisulfate, or initiator combination systems are used as polymerization initiators, the polymerization temperature in the case of the thermal to be activated ammonium and Alkyliperoxodisulfate at 50 should be up to 100 ° C.

The European Patent EP 0 828 772 B1 describes the toughening of poly (meth) acrylates by means of multistage core-shell particles which consist of a core, a first shell and optionally a second shell and are free from vinylically unsaturated compounds having at least two identically reactive double bonds. The core contains a first (Meth) acrylic polymer. The first shell comprises a polymer having a low glass transition temperature, which comprises 0 to 25% by weight, in particular 5 to 26% by weight, of a styrenic monomer and 75 to 100% by weight of a (meth) acrylic monomer containing a homopolymer a glass transition temperature between -75 and -5 ° C forms comprises. The optional second shell contains a second (meth) acrylic polymer which may be the same as or different from the first (meth) acrylic polymer. The total diameter of the core-shell particles is in the range of 250 to 320 nm.

The core-shell particles are again produced by multistage emulsion polymerization at 80 ° C., using potassium persulfate as the initiator.

Although the methods described above are commonly used in the production of core-shell particles, they all have the disadvantage that the polymerization is carried out at a comparatively low monomer concentration, i. a. less than 50.0% by weight, in order to obtain the desired particle sizes with a narrow particle size distribution. By contrast, polymerization at a higher monomer concentration leads to a significant widening of the particle size distribution and to the formation of large amounts of coagulum, which markedly worsens the material properties of the core-shell particles.

For the application, in particular for the toughening of molding compositions, the core-shell particles can not be used as an aqueous dispersion, but instead have to be isolated from the aqueous dispersion. Thus, the low solids content of the aqueous dispersion has a direct adverse effect on the possible use of the above-mentioned core-shell particles, since their separation requires a great deal of energy and other resources. More efficient processes are therefore needed to produce core-shell particles.

In addition to the emulsion polymers, suspension polymers are also occasionally used for the toughening of molding compositions. Here, the rubber grafted with, for example, polymethyl methacrylate is relatively finely distributed in the matrix of the molding composition, for example polymethyl methacrylate. The elastomeric phase consists of a mostly crosslinked copolymer having a low glass transition temperature below 25 ° C., which usually have alkyl acrylate units having 1 to 8 carbon atoms in the alkyl radical, in particular butyl acrylate units, as the main component. Occasionally, polybutadiene or polybutadiene copolymers are used as a tough phase.

Although a significant improvement in notched impact strength can be achieved even using the impact modifiers described above, this is not yet completely satisfactory for many applications. In particular, the toughening at room temperature (23 ° C) requires a relatively large amount of these impact modifiers, which in turn to a significant deterioration of other important for the application properties of the molding composition, in particular the modulus of elasticity, the melt viscosity, the Vicat temperature and the strand expansion, leads.

The technique therefore requires impact modifiers which, with the smallest possible amounts of impact modifier, allow a sufficient improvement in the notched impact strength of a molding compound, in particular at room temperature, without simultaneously reducing the other important properties of the molding compound, in particular the modulus of elasticity, the melt viscosity, the Vicat Temperature and the strand expansion, are noticeably deteriorated. The molding composition should have an impact strength according to Charpy (ISO 179) at 23 ° C., preferably at least 6.0 kJ / m ² and at -10 ° C., preferably at least 2.5 kJ / m ² , an E modulus (ISO 527-2 ) preferably greater than 1500 MPa, a haze according to ASTM D 1003 (1997) of preferably maximum 2.5%, a melt viscosity preferably greater than 2000 Pa s and favorably less than 4500 Pa s, a Vicat softening temperature preferably of at least 85 ° C, favorably of at least 90 ° C, in particular of at least 93 ° C, a transmission (D 65 / 10 °) according to DIN 5033/5036 of preferably at least 88.5% and a strand expansion preferably in the range of 0 to 20%.

In view of the prior art, it was an object of the present invention to provide toughening modifiers for molding compositions, in particular for poly (meth) acrylate molding compositions, which allow an improvement in the notched impact strength of molding compositions, in particular at room temperature, without simultaneously other, for the application significant properties of the molding composition, in particular the modulus of elasticity, the melt viscosity, the Vicat temperature and the strand expansion, to deteriorate markedly. In this case, the molding compositions should have an impact strength according to Charpy (ISO 179) at 23 ° C., preferably at least 6.0 kJ / m ² and at -10 ° C., preferably at least 2.5 kJ / m ² , an E modulus (ISO 527-2 ) preferably greater than 1500 MPa, a haze according to ASTM D 1003 (1997) of preferably at most 2.5%, a melt viscosity preferably greater than 2000 Pa s and favorably less than 4500 Pa s, a Vicat softening temperature preferably of at least 85 ° C, desirably from at least 90 ° C, in particular of at least 93 ° C, a transmission (D 65/10 °) according to DIN 5033/5036 of preferably at least 88.5% and a strand expansion preferably in the range of 0 to 20%.

Another object of the present invention was to provide a more efficient method of producing core-shell particles, which in particular allows less expensive isolation of the core-shell particles.

An object of the present invention was also to be seen to provide a method for the production of core-shell particles, which simple manner, on an industrial scale and cost feasible.

A further object of the present invention was to provide a process for producing core-shell particles having the smallest possible particle size distribution, preferably having a U ₈₀ value of less than 0.22.

The object of the present invention was also to find a process for the production of core-shell particles, in which as little as possible, preferably less than 5.0 wt .-%, coagulum is formed.

In addition, another object of the present invention was to provide a method for producing core-shell particles having a particle radius, measured by the Coulter method, in the range from 150.0 to less than 250.0 nm, since these core particles Shell particles are particularly suitable for the impact modification of molding compositions, in particular of polyalkyl (meth) acrylate molding composition.

These and other objects which are not explicitly mentioned, but which are readily derivable or deducible from the contexts discussed hereinbelow, are solved by a process for producing an aqueous dispersion having all the features of present claim 1. Advantageous modifications of the procedure according to the invention are disclosed in US Pat Claim 1 related back claims protected. Product claim 11 protects the core-shell particles obtainable by the process. Furthermore, impact-modified poly (meth) acrylate molding compositions which contain core-shell particles according to the invention and preferred fields of use of these molding compositions are claimed.

1. a) Wasser und Emulgator vorlegt,
2. b) 25,0 bis 45,0 Gew.-Teile einer ersten Zusammensetzung enthaltend
   1. A) 50,0 bis 99,9 Gew.- Teile von C) verschiedene Alkylmethacrylate mit 1 bis 20 Kohlenstoffatomen im Alkylrest,
   2. B) 0,0 bis 40,0 Gew.- Teile von C) verschiedene Alkylacrylate mit 1 bis 20 Kohlenstoffatomen im Alkylrest,
   3. C) 0,1 bis 10,0 Gew.- Teile vernetzende Monomere und
   4. D) 0,0 bis 8,0 Gew.- Teile styrolische Monomere der allgemeinen Formel (I)
      
      wobei die Reste R¹ bis R⁵ jeweils unabhängig voneinander Wasserstoff, ein Halogen, eine C_1-6-Alkylgruppe oder eine C_2-6-Alkenylgruppe bezeichnen und der Rest R⁶ Wasserstoff oder eine Alkylgruppe mit 1 bis 6 Kohlenstoffatomen ist,
   zugibt und bis zu einem Umsatz von mindestens 85,0 Gew.-%, bezogen auf das Gesamtgewicht der Komponenten A), B), C) und D), polymerisiert,
3. c) 35,0 bis 55,0 Gew.-Teile einer zweiten Zusammensetzung enthaltend
   • E) 80,0 bis 100,0 Gew.- Teile (Meth)acrylate
   • F) 0,05 bis 10,0 Gew.-Teile vernetzende Monomere und
   • G)0,0 bis 20,0 Gew.- Teile styrolische Monomere der allgemeinen Formel (I),
   zugibt und bis zu einem Umsatz von mindestens 85,0 Gew.-%, bezogen auf das Gesamtgewicht der Komponenten E), F) und G), polymerisiert,
4. d) 10,0 bis 30,0 Gew.-Teile einer dritten Zusammensetzung enthaltend
   • H) 50,0 bis 100,0 Gew.- Teile Alkylmethacrylate mit 1 bis 20 Kohlenstoffatomen im Alkylrest,
   • I) 0,0 bis 40,0 Gew.- Teile Alkylacrylate mit 1 bis 20 Kohlenstoffatomen im Alkylrest und
   • J) 0,0 bis 10,0 Gew.- Teile styrolische Monomere der allgemeinen Formel (I)
     zugibt und bis zu einem Umsatz von mindestens 85,0 Gew.-%, bezogen auf das Gesamtgewicht der Komponenten H), I) und J), polymerisiert,
   wobei sich die angegebenen Gewichtsteile der Zusammensetzungen b), c) und d) zu 100,0 Gewichtsteilen addieren und
   sich das Verfahren dadurch auszeichnet, dass man
5. e) die jede Polymerisation bei einer Temperatur im Bereich von >60 bis < 90 °C durchführt und
6. f) die relativen Anteile aller Substanzen derart wählt, dass das Gesamtgewicht der Komponenten A) bis J), bezogen auf das Gesamtgewicht der wässrigen Dispersion, größer 50,0 Gew.-% ist,

gelingt es auf nicht ohne weiteres vorhersehbare Weise, ein Verfahren zugänglich zu machen, welches die effiziente Herstellung von Kern-Schale-Teilchen in wässriger Dispersion erlaubt. Dabei wird durch den hohen Feststoffgehalt der wässrigen Dispersion die Separation der Kern-Schale-Teilchen gegenüber den herkömmlichen Verfahren wesentlich erleichtert.By providing a process for the preparation of an aqueous dispersion which comprises:

1. a) presenting water and emulsifier,
2. b) containing 25.0 to 45.0 parts by weight of a first composition
   1. A) 50.0 to 99.9 parts by weight of C) various alkyl methacrylates having 1 to 20 carbon atoms in the alkyl radical,
   2. B) 0.0 to 40.0 parts by weight of C) various alkyl acrylates having 1 to 20 carbon atoms in the alkyl radical,
   3. C) 0.1 to 10.0 parts by weight of crosslinking monomers and
   4. D) 0.0 to 8.0 parts by weight of styrenic monomers of the general formula (I)
      
      wherein the radicals R ¹ to R ⁵ each independently of one another denote hydrogen, a halogen, a C _1-6 -alkyl group or a C _2-6 -alkenyl group and the radical R ^{6 is} hydrogen or an alkyl group having 1 to 6 carbon atoms,
   admixed and polymerized to a conversion of at least 85.0% by weight, based on the total weight of components A), B), C) and D),
3. c) containing 35.0 to 55.0 parts by weight of a second composition
   • E) 80.0 to 100.0 parts by weight of (meth) acrylates
   • F) 0.05 to 10.0 parts by weight of crosslinking monomers and
   • G) 0.0 to 20.0 parts by weight of styrenic monomers of the general formula (I),
   admixed and polymerized to a conversion of at least 85.0% by weight, based on the total weight of components E), F) and G),
4. d) containing 10.0 to 30.0 parts by weight of a third composition
   • H) 50.0 to 100.0 parts by weight of alkyl methacrylates having 1 to 20 carbon atoms in the alkyl radical,
   • I) 0.0 to 40.0 parts by weight of alkyl acrylates having 1 to 20 carbon atoms in the alkyl radical and
   • J) 0.0 to 10.0 parts by weight of styrenic monomers of the general formula (I)
     and up to a conversion of at least 85.0 wt .-%, based on the total weight of components H), I) and J), polymerized,
   wherein the specified parts by weight of the compositions b), c) and d) add up to 100.0 parts by weight and
   the process is characterized in that one
5. e) which carries out each polymerization at a temperature in the range of> 60 to <90 ° C and
6. f) the relative proportions of all substances are selected such that the total weight of components A) to J), based on the total weight of the aqueous dispersion, is greater than 50.0% by weight,

In a way that is not readily predictable, it is possible to make available a process which allows the efficient production of core-shell particles in aqueous dispersion. Due to the high solids content of the aqueous dispersion, the separation of the core-shell particles compared to the conventional methods is substantially facilitated.

• ⇒ Das erfindungsgemäße Verfahren ist auf einfache Art und Weise großtechnisch und kostengünstig durchführbar.
• ⇒ Die durch das erfindungsgemäße Verfahren erhältlichen Kern-Schale-Teilchen zeichnen sich durch eine enge Teilchengrößenverteilung, vorzugsweise einem U₈₀-Wert kleiner 0,22, aus.
• ⇒ Die Bildung von Koagulat wird beim erfindungsgemäßen Verfahren nahezu vollständig unterdrückt.
• ⇒ Das erfindungsgemäße Verfahren eignet sich insbesondere für die Herstellung von Kern-Schale-Teilchen mit einem Teilchenradius, gemessen nach dem Coulter-Verfahren, im Bereich von 150,0 bis kleiner 250,0 nm.
• ⇒ Durch das erfindungsgemäße Verfahren werden Schlagzähmodifizierer für Formmassen, insbesondere für Poly(meth)acrylat-Formmassen bereitgestellt, welche eine Verbesserung der Kerbschlagzähigkeit von Formmassen, insbesondere bei Raumtemperatur, ermöglichen, ohne gleichzeitig die anderen, für die Anwendung bedeutenden Eigenschaften der Formmasse, insbesondere der E-Modul, die Schmelzviskosität, die Vicat-Temperatur und die Strangaufweitung, merklich zu verschlechtern. Dabei weisen erfindungsgemäß besonders geeignete Formmassen eine Kerbschlagzähigkeit nach Charpy (ISO 179) bei 23 °C vorzugsweise mindestens 6,0 kJ/m² und bei -10 °C vorzugsweise mindestens 2,5 kJ/m², ein E-Modul (ISO 527-2) vorzugsweise größer 1500 MPa, einen Haze nach ASTM D 1003 (1997) von vorzugsweise maximal 2,5 %, eine Schmelzviskosität vorzugsweise größer 2000 Pa s und günstigerweise kleiner 4500 Pa s, eine Vicat-Erweichungstemperatur vorzugsweise von mindestens 85 °C, günstigerweise von mindestens 90 °C, insbesondere von mindestens 93 °C, eine Transmission (D 65/10°) nach DIN 5033/5036 von vorzugsweise mindestens 88,5 % sowie eine Strangaufweitung vorzugsweise im Bereich von 0 bis 20 % auf.
• ⇒ Durch Verwendung der erfindungsgemäßen Kern-Schale-Teilchen werden Formmassen mit deutlich verbesserten Kerbschlägzähigkeit-Werten, insbesondere bei tiefen Temperaturen kleiner 0 °C, zweckmäßigerweise Formmassen mit einer Kerbschlagzähigkeit nach Izod gemäß ISO 180 von mindestens 3,5 kJ/m² bei -10 °C, zugänglich.
• ⇒ Im Vergleich mit herkömmlichen Schlagzähmodifizierern reichen deutlich geringere Mengen der erfindungsgemäßen Kern-Schale-Teilchen aus, um Formmassen mit vergleichbaren Kerbschlagzähigkeiten bei Raumtemperatur, insbesondere bei 23 °C, zu erhalten.
• ⇒ Die auf erfindungsgemäße Weise schlagzähmodifizierten Formmassen zeichnen sich durch ein deutlich verbessertes Eigenschaftsprofil bei Raumtemperatur, insbesondere bei 23 °C, aus. Dies prädestiniert sie für Anwendungen diesen Temperaturen, insbesondere bei Temperaturen im Bereich von 0 °C bis 50 °C.

In addition, a number of further advantages can be achieved by the procedure according to the invention. These include:

• ⇒ The method according to the invention can be carried out in a simple manner on an industrial scale and inexpensively.
• ⇒ The core-shell particles obtainable by the process according to the invention are distinguished by a narrow particle size distribution, preferably a U ₈₀ value of less than 0.22.
• ⇒ The formation of coagulum is almost completely suppressed in the process according to the invention.
• ⇒ The inventive method is particularly suitable for the production of core-shell particles having a particle radius, measured by the Coulter method, in the range of 150.0 to less than 250.0 nm.
• The process according to the invention provides toughening modifiers for molding compositions, in particular for poly (meth) acrylate molding compositions, which make it possible to improve the impact strength of molding compositions, in particular at room temperature, without at the same time suppressing the other properties of the molding composition which are important for the application, in particular Young's modulus, the melt viscosity, the Vicat temperature and the strand expansion, deteriorate markedly. Particularly suitable molding compositions according to the invention have an impact strength according to Charpy (ISO 179) at 23 ° C., preferably at least 6.0 kJ / m ² and at -10 ° C., preferably at least 2.5 kJ / m ² , an E modulus (ISO 527 -2) preferably greater than 1500 MPa, a haze according to ASTM D 1003 (1997) of preferably at most 2.5%, a melt viscosity preferably greater than 2000 Pa s and favorably less than 4500 Pa s, a Vicat softening temperature preferably of at least 85 ° C, favorably of at least 90 ° C, in particular of at least 93 ° C, a transmission (D 65/10 °) according to DIN 5033/5036 of preferably at least 88.5% and a strand expansion preferably in the range of 0 to 20%.
• By using the core-shell particles of the invention, molding compositions having significantly improved indentability values, in particular at low temperatures of less than 0 ° C., advantageously molding compositions having an Izod impact strength according to ISO 180 of at least 3.5 kJ / m ² at -10 ° C, accessible.
• ⇒ In comparison with conventional impact modifiers, significantly lower amounts of the core-shell particles according to the invention are sufficient to obtain molding compositions having comparable notched impact strength values at room temperature, in particular at 23 ° C.
• ⇒ The molding compositions which are impact-modified according to the invention are distinguished by a markedly improved property profile at room temperature, in particular at 23 ° C. This predestines them for applications at these temperatures, in particular at temperatures in the range of 0 ° C to 50 ° C.

According to the present invention, the preparation of an aqueous dispersion is carried out by a process in which water and emulsifier are introduced. In this case, the template preferably contains 90.00 to 99.99 parts by weight of water and 0.01 to 10.00 parts by weight of emulsifier, wherein the specified parts by weight add up favorably to 100.00 parts by weight.

• b) 25,0 bis 45,0 Gew.-Teile einer ersten Zusammensetzung zugegeben und bis zu einem Umsatz von mindestens 85,0 Gew.-%, vorzugsweise mindestens 90,0 Gew.-%, zweckmäßigerweise mindestens 95,0 Gew.-%, insbesondere mindestens 99 Gew.-%, jeweils bezogen auf das Gesamtgewicht der Komponenten A), B), C) und D), polymerisiert,
• c) 35,0 bis 55,0 Gew.-Teile einer zweiten Zusammensetzung zugegeben und bis zu einem Umsatz von mindestens 85,0 Gew.-%, vorzugsweise mindestens 90,0 Gew.-%, zweckmäßigerweise mindestens 95,0 Gew.-%, insbesondere mindestens 99 Gew.-%, jeweils bezogen auf das Gesamtgewicht der Komponenten E), F) und G), polymerisiert,
• d) 10,0 bis 30,0 Gew.-Teile einer dritten Zusammensetzung zugegeben und bis zu einem Umsatz von mindestens 85,0 Gew.-%, vorzugsweise mindestens 90,0 Gew.-%, zweckmäßigerweise mindestens 95,0 Gew.-%, insbesondere mindestens 99 Gew.-%, jeweils bezogen auf das Gesamtgewicht der Komponenten H), I) und J), polymerisiert,

wobei sich die angegebenen Gewichtsteile zu 100,0 Gewichtsteilen addieren.This template will then be step by step in the following order

• b) 25.0 to 45.0 parts by weight of a first composition and up to a conversion of at least 85.0 wt .-%, preferably at least 90.0 wt .-%, suitably at least 95.0 wt. %, in particular at least 99 wt .-%, in each case based on the total weight of components A), B), C) and D), polymerized,
• c) 35.0 to 55.0 parts by weight of a second composition and up to a conversion of at least 85.0 wt .-%, preferably at least 90.0 wt .-%, advantageously at least 95.0 wt. %, in particular at least 99 wt .-%, each based on the total weight of components E), F) and G), polymerized,
• d) 10.0 to 30.0 parts by weight of a third composition and up to a conversion of at least 85.0 wt .-%, preferably at least 90.0 wt .-%, preferably at least 95.0 wt. %, in particular at least 99 wt .-%, each based on the total weight of components H), I) and J), polymerized,

wherein the specified parts by weight add up to 100.0 parts by weight.

In the context of the present invention, polymers are compounds which have at least ten times the molecular weight in comparison with the particular starting compound A) to J), the so-called monomer.

The tracking of the progress of the polymerization in each step may be carried out in a known manner, for example gravimetrically or by gas chromatography.

• A)50,0 bis 99,9 Gew.-Teile, zweckmäßigerweise 60,0 bis 99,9 Gew.-Teile, vorzugsweise 75,0 bis 99,9 Gew.-Teile, insbesondere 85,0 bis 99,5 Gew.- Teile, Alkylmethacrylate mit 1 bis 20, vorzugsweise 1 bis 12, insbesondere 1 bis 8, Kohlenstoffatomen im Alkylrest,
• B) 0,0 bis 40,0 Gew.-Teile, vorzugsweise 0,0 bis 24,9 Gew.-Teile, insbesondere 0,1 bis 14,9 Gew.- Teile, Alkylacrylate mit 1 bis 20, vorzugsweise 1 bis 12, insbesondere 1 bis 8, Kohlenstoffatomen im Alkylrest,
• C) 0,1 bis 10,0 Gew.-Teile, vorzugsweise 0,1 bis 5,0 Gew.-Teile, insbesondere 0,1 bis 2,0 Gew.-Teile, vernetzende Monomere und
• D)0,0 bis 8,0 Gew.-Teile styrolische Monomere der allgemeinen Formel (1)
  
  wobei sich die angegebenen Gewichtsteile vorzugsweise zu 100,0 Gew.-Teile ergänzen.

The first composition contains

• A) 50.0 to 99.9 parts by weight, advantageously 60.0 to 99.9 parts by weight, preferably 75.0 to 99.9 parts by weight, in particular 85.0 to 99.5 wt. Parts, alkyl methacrylates having 1 to 20, preferably 1 to 12, in particular 1 to 8, carbon atoms in the alkyl radical,
• B) 0.0 to 40.0 parts by weight, preferably 0.0 to 24.9 parts by weight, in particular 0.1 to 14.9 parts by weight, alkyl acrylates having 1 to 20, preferably 1 to 12 , in particular 1 to 8, carbon atoms in the alkyl radical,
• C) 0.1 to 10.0 parts by weight, preferably 0.1 to 5.0 parts by weight, in particular 0.1 to 2.0 parts by weight, of crosslinking monomers and
• D) 0.0 to 8.0 parts by weight of styrenic monomers of the general formula (1)
  
  wherein the specified parts by weight preferably add up to 100.0 parts by weight.

Of course, the compounds A), B), C) and D) are different from each other, in particular, the compounds A) and B) comprise no crosslinking monomers C).

The radicals R ¹ to R ⁵ each independently denote hydrogen, a halogen, in particular fluorine, chlorine or bromine, or an alkyl group having 1 to 6 carbon atoms, preferably hydrogen. The radical R ⁶ denotes hydrogen or an alkyl group having 1 to 6 carbon atoms, preferably hydrogen. Particularly suitable alkyl groups having 1 to 6 carbon atoms are methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl and Cyclopentyl and cyclohexyl groups.

Thus, styrenic monomers of general formula (I) include styrene, substituted styrenes having an alkyl substituent in the side chain, such as α-methylstyrene and α-ethylstyrene, substituted styrenes having an alkyl substituent on the ring, such as vinyltoluene! and p-methylstyrene, halogenated styrenes. such as monochlorostyrenes, dichlorostyrenes, tribromostyrenes and tetrabromostyrenes.

The above-mentioned alkyl methacrylates (A) are understood as meaning esters of methacrylic acid, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, 2-octyl methacrylate, ethylhexyl methacrylate, nonyl methacrylate , 2-methyloctylmethacrylate, 2-tert-butylheptylmethacrylate, 3-isopropyl-propylmethacrylate, decylmethacrylate, undecylmethacrylate, 5-methylundecylmethacrylate, dodecylmethacrylate, 2-methyldodecylmethacrylate, tridecylmethacrylate, 5-methyltridecylmethacrylate, tetradecylmethacrylate, pentadecylmethacrylate, hexadecylmethacrylate, 2-methylhexadecylmethacrylate, heptadecylmethacrylate, 5-iso-propylheptadecyl methacrylate, 5-ethyloctadecyl methacrylate, octadecyl methacrylate, nonadecyl methacrylate, Eicosyl methacrylate, cycloalkyl methacrylates such as cyclopentyl methacrylate, cyclohexyl methacrylate, 3-vinyl-2-butyl-cyclohexyl methacrylate, cycloheptyl methacrylate, cyclooctyl methacrylate, bornyl methacrylate and isobornyl methacrylate.

According to a particularly preferred embodiment of the present invention, the first composition, based on the total weight of components A) to D), contains at least 50% by weight, advantageously at least 60% by weight, preferably at least 75% by weight, in particular at least 85% by weight of methyl methacrylate.

The alkyl acrylates (B) mentioned above are understood as meaning esters of acrylic acid, for example methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, tert-butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-octyl acrylate, ethylhexyl acrylate, nonyl acrylate , 2-methyl-octylacrylate, 2-tert-butylheptylacrylate, 3-iso-propylheptylacrylate, decylacrylate, undecylacrylate, 5-methylundecylacrylate, dodecylacrylate, 2-methyldodecylacrylate, tridecylacrylate, 5-methyltridecylacrylate, tetradecylacrylate, pentadecylacrylate, hexadecylacrylate, 2-methylhexadecylacrylate, Heptadecyl acrylate, 5-isopropylheptadecylacrylate, 5-ethyloctadecylacrylate, octadecylacrylate, nonadecylacrylate, eicosylacrylate, cycloalkylacrylates such as cyclopentylacrylate, cyclohexylacrylate, 3-vinyl-2-butylcyclohexylacrylate, cycloheptylacrylate, cyclooctylacrylate, bornylacrylate and isobornylacrylate.

1. (a) Difunktionelle (Meth)acrylate, vorzugsweise Verbindungen der allgemeinen Formel:
   
   worin R Wasserstoff oder Methyl ist und n eine positive ganze Zahl größer gleich 2, vorzugsweise zwischen 3 und 20 bezeichnet, insbesondere Di(meth)acrylate des Propandiols, Butandiols, Hexandiols, Octandiols, Nonandiols, Decandiols und des Eicosandiols;
   Verbindungen der allgemeinen Formel:
   
   worin R Wasserstoff oder Methyl ist und n eine positive ganze Zahl zwischen 1 und 14 bedeutet, insbesondere Di(meth)acrylate des Ethylenglycols, Diethylenglycols, Triethylenglycols, Tetraethylenglycols, Dodecaethylenglycols, Tetradecaethylenglycols, Propylenglycols, Dipropylglycols und des Tetradecapropylenglycols.
   Glycerindi(meth)acrylat, 2,2'- Bis[p-(γ-methacryloxy-β-hydroxypropoxy)-phenylpropan] oder Bis-GMA, Biphenol-A-dimethacrylat, Neopentylglycoldi(meth)acrylat, 2,2'-Di(4-methacryloxypolyethoxyphenyl)propan mit 2 bis 10 Ethoxygruppen pro Molekül und 1,2-Bis(3-methacryloxy-2- hydroxypropoxy)butan.
2. (b) Tri- oder polyfunktionelle (Meth)acrylate, insbesondere Trimethylolpropantri(meth)acrylate und Pentaerythritoltetra(meth)acrylat.
3. (c) Pfropfvernetzer mit mindestens zwei unterschiedlich reaktiven C-C-Doppelbindungen, insbesondere Allylmethacrylat und Allylacrylat;
4. (d) aromatische Vernetzer, insbesondere 1,2-Divinylbenzol, 1,3-Divinylbenzol und 1,4-Divinylbenzol.

Crosslinking monomers (C) include any of the compounds capable of crosslinking under the present polymerization conditions. These include in particular

1. (a) Difunctional (meth) acrylates, preferably compounds of the general formula:
   
   wherein R is hydrogen or methyl and n denotes a positive integer greater than or equal to 2, preferably between 3 and 20, in particular di (meth) acrylates of propanediol, butanediol, hexanediol, octanediol, nonanediol, decanediol and eicosanediol;
   Compounds of the general formula:
   
   wherein R is hydrogen or methyl and n is a positive integer between 1 and 14, in particular di (meth) acrylates of ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dodecaethylene glycols, tetradecaethylene glycols, propylene glycols, dipropylglycols and tetradecapropylene glycol.
   Glycerol di (meth) acrylate, 2,2'-bis [p- (γ-methacryloxy-β-hydroxypropoxy) phenylpropane] or bis-GMA, biphenol A dimethacrylate, neopentyl glycol di (meth) acrylate, 2,2'-di (4-Methacryloxypolyethoxyphenyl) propane having 2 to 10 ethoxy groups per molecule and 1,2-bis (3-methacryloxy-2-hydroxypropoxy) butane.
2. (b) Tri- or polyfunctional (meth) acrylates, in particular trimethylolpropane tri (meth) acrylates and pentaerythritol tetra (meth) acrylate.
3. (C) graft crosslinker having at least two differently reactive CC double bonds, in particular allyl methacrylate and allyl acrylate;
4. (d) aromatic crosslinkers, especially 1,2-divinylbenzene, 1,3-divinylbenzene and 1,4-divinylbenzene.

wobei X_n für den Massebruch (Gew.-%/100) des Monomeren n steht und Tg_n die Glasübergangstemperatur in Kelvin des Homopolymeren des Monomeren n bezeichnet. Weitere hilfreiche Hinweise kann der Fachmann dem Polymer Handbook 2nd Edition, J. Wiley & Sons, New York (1975 ) entnehmen, welche Tg-Werte für die geläufigsten Homopolymerisate angibt.The monomer selection or the selection of the proportions by weight of the monomers A) to D) of the first composition is preferably carried out in such a way that the polymerization of the first monomer mixture polymer obtainable has a glass transition temperature Tg of at least 10 ° C, preferably of at least 30 ° C. In this case, the glass transition temperature Tg of the polymer can be determined in a known manner by means of differential scanning calorimetry (DSC). Furthermore, the glass transition temperature Tg can also be calculated approximately in advance by means of the Fox equation. To Fox TG, Bull. Physics Soc. 1, 3, page 123 (1956 ) applies: $$\frac{1}{\mathit{Tg}}=\frac{x_1}{{\mathit{Tg}}_1}+\frac{x_2}{{\mathit{Tg}}_2}+...+\frac{x_n}{{\mathit{Tg}}_n}$$

wherein X _n is the mass fraction (wt .-% / 100) of monomer n and Tg _{n is} the glass transition temperature in Kelvin of the homopolymer of the monomer n denotes. Further helpful hints can the specialist the Polymer Handbook 2nd Edition, J. Wiley & Sons, New York (1975 ), which indicates Tg values for the most common homopolymers.

• E) 80,0 bis 100,0 Gew.-Teile, vorzugsweise 92,0 bis 98,0 Gew.-Teile, von F) verschiedene (Meth)acrylate
• F) 0,05 bis 10,0 Gew.-%-Teile, vorzugsweise 0,1 bis 2,0 Gew.-%, vernetzende Monomere und
• G)0,0 bis 20,0 Gew.-Teile, vorzugsweise 8,0 bis 20,0 Gew.-Teile styrolische Monomere der allgemeinen Formel (I),

wobei sich die angegebenen Gewichtsteile vorzugsweise zu 100,0 Gew.-Teile addieren.The second monomer mixture contains

• E) 80.0 to 100.0 parts by weight, preferably 92.0 to 98.0 parts by weight, of (F) different (meth) acrylates
• F) 0.05 to 10.0 wt .-% - parts, preferably 0.1 to 2.0 wt .-%, crosslinking monomers and
• G) 0.0 to 20.0 parts by weight, preferably 8.0 to 20.0 parts by weight of styrenic monomers of the general formula (I),

wherein the specified parts by weight preferably add up to 100.0 parts by weight.

Of course, the compounds E), F) and G) are different from each other, in particular the compounds E) comprise no crosslinking monomers F).

wobei R Wasserstoff oder einen Methylrest kennzeichnet. Zu ihnen gehören insbesondere die vorstehend genannten Alkylacrylate und Alkylmethacrylate. Weiterhin haben sich auch Arylalkylacrylate, insbesondere Benzyl-, Phenylethyl-, Phenylpropyl-, Phenylpentyl-und/oder Phenylhexylacrylat, für die Zwecke der vorliegenden Erfindung als besonders nützlich erwiesen. Sie werden vorzugsweise in einer Menge im Bereich von 0,1 bis 40,0 Gew.-%, bezogen auf das Gesamtgewicht der Komponenten E) und F), eingesetzt.In the context of the present invention, (meth) acrylates, acrylates, methacrylates and mixtures of both. They thus include Compounds which have at least one group of the following formula

where R denotes hydrogen or a methyl radical. These include in particular the abovementioned alkyl acrylates and alkyl methacrylates. Furthermore, arylalkyl acrylates, especially benzyl, phenylethyl, phenylpropyl, phenylpentyl and / or phenylhexyl acrylate, have also proved particularly useful for the purposes of the present invention. They are preferably used in an amount in the range of 0.1 to 40.0 wt .-%, based on the total weight of components E) and F).

The crosslinking monomers F) according to the invention comprise the above-mentioned crosslinking monomers C).

• E) 90,0 bis 97,9 Gew.-Teile Alkylacrylate mit 3 bis 8 Kohlenstoffatomen im Alkylrest und/oder Alkylmethacrylate mit 7 bis 14 Kohlenstoffatomen im Alkylrest, insbesondere Butylacrylat und/oder Dodecylmethacrylat,
• F) 0,1 bis 2,0 Gew.-% vernetzende Monomere und
• G) 0,0 bis 20,0 Gew.-Teile, vorzugsweise 8,0 bis 20,0 Gew.-Teile styrolische Monomere der allgemeinen Formel (I),

wobei sich die Gewichtsteile vorzugsweise zu 100,0 Gew.-Teilen addieren.In a very particularly preferred embodiment of the present invention, the second monomer mixture comprises

• E) 90.0 to 97.9 parts by weight of alkyl acrylates having 3 to 8 carbon atoms in the alkyl radical and / or alkyl methacrylates having 7 to 14 carbon atoms in the alkyl radical, in particular butyl acrylate and / or dodecyl methacrylate,
• F) 0.1 to 2.0 wt .-% of crosslinking monomers and
• G) 0.0 to 20.0 parts by weight, preferably 8.0 to 20.0 parts by weight of styrenic monomers of the general formula (I),

wherein the parts by weight preferably add up to 100.0 parts by weight.

Furthermore, the monomer selection or the selection of the proportions by weight of the monomers E), F) and G) of the second composition is advantageously carried out in such a way that the polymer obtainable by the polymerization of the second composition has a glass transition temperature Tg of less than 30 ° C., preferably less than 10 ° C., in particular in the range of 0 to -75 ° C, having. In this case, the glass transition temperature Tg of the polymer, as already mentioned above, can be determined by means of differential scanning calorimetry (DSC) and / or calculated approximately in advance by means of the Fox equation.

• H) 50,0 bis 100,0 Gew.-Teile, zweckmäßigerweise 60,0 bis 100,0 Gew.-Teile, besonders bevorzugt 75,0 bis 100,0 Gew.-Teile, insbesondere 85,0 bis 99,5 Gew.- Teile, Alkylmethacrylate mit 1 bis 20, vorzugsweise 1 bis 12, insbesondere 1 bis 8, Kohlenstoffatomen im Alkylrest,
• I) 0,0 bis 40,0 Gew.-Teile, vorzugsweise 0,0 bis 25,0 Gew.-Teile, insbesondere 0,1 bis 15,0 Gew.- Teile, Alkylacrylate mit 1 bis 20, vorzugsweise 1 bis 12, insbesondere 1 bis 8, Kohlenstoffatomen im Alkylrest,
• J) 0,0 bis 10,0 Gew.-Teile, vorzugsweise 0,0 bis 8,0 Gew.-% styrolische Monomere der allgemeinen Formel (I),

wobei dich die angegebenen Gewichtsteile vorzugsweise zu 100,0 Gew.-Teile addieren.The third composition contains

• H) 50.0 to 100.0 parts by weight, suitably 60.0 to 100.0 parts by weight, particularly preferably 75.0 to 100.0 parts by weight, in particular 85.0 to 99.5 wt Parts, alkyl methacrylates having 1 to 20, preferably 1 to 12, in particular 1 to 8, carbon atoms in the alkyl radical,
• I) from 0.0 to 40.0 parts by weight, preferably from 0.0 to 25.0 parts by weight, in particular from 0.1 to 15.0 parts by weight, of alkyl acrylates having from 1 to 20, preferably from 1 to 12 , in particular 1 to 8, carbon atoms in the alkyl radical,
• J) from 0.0 to 10.0 parts by weight, preferably from 0.0 to 8.0% by weight, of styrenic monomers of the general formula (I),

wherein the specified parts by weight preferably add up to 100.0 parts by weight.

According to a particularly preferred embodiment of the present invention, the third composition, based on the total weight of components H) to J), at least 50 wt .-%, advantageously at least 60 wt .-%, preferably at least 75 wt .-%, in particular at least 85% by weight of methyl methacrylate.

Furthermore, the monomer selection or the selection of the weight proportions of the monomers H), I) and J) of the third composition is conveniently carried out such that the polymer obtainable by the polymerization of the third composition has a glass transition temperature Tg of at least 10 ° C, preferably of at least 30 ° C, has. In this case, the glass transition temperature Tg of the polymer, as already mentioned above, can be determined by means of differential scanning calorimetry (DSC) and / or calculated approximately in advance by means of the Fox equation.

In the process according to the invention, the polymerization in steps b) to d) takes place at a temperature in the range from greater than 60 to less than 90 ° C., advantageously in the range from greater than 70 to less than 85 ° C., preferably in the range from greater than 75 to less than 85 ° C.

The initiation takes place with the initiators customary for emulsion polymerization. Suitable organic initiators are, for example, hydroperoxides, such as tert-butyl hydroperoxide or cumene hydroperoxide. Suitable inorganic initiators are hydrogen peroxide and the alkali metal and ammonium salts of peroxodisulfuric acid, in particular sodium and potassium peroxodisulfate. The initiators mentioned can be used both individually and in mixtures. They are preferably used in an amount of 0.05 to 3.0 wt .-%, based on the total weight of the monomers of each stage.

• * Alkylsulfate, vorzugsweise solche mit 8 bis 18 Kohlenstoffatomen im Alkylrest, Alkyl- und Alkylarylethersulfate mit 8 bis 18 Kohlenstoffatomen im Alkylrest und 1 bis 50 Ethylenoxideinheiten;
• * Sulfonate, vorzugsweise Alkylsulfonate mit 8 bis 18 Kohlenstoffatomen im Alkylrest, Alkylarylsulfonate mit 8 bis 18 Kohlenstoffatomen im Alkylrest, Ester und Halbester der Sulfobernsteinsäure mit einwertigen Alkoholen oder Alkylphenolen mit 4 bis 15 Kohlenstoffatomen im Alkylrest; gegebenenfalls können diese Alkohole oder Alkylphenole auch mit 1 bis 40 Ethylenoxideinheiten ethoxyliert sein;
• * Phosphorsäureteilester und deren Alkali- und Ammoniumsalze, vorzugsweise Alkyl- und Alkylarylphosphate mit 8 bis 20 Kohlenstoffatomen im Alkyl- bzw. Alkylarylrest und 1 bis 5 Ethylenoxideinheiten;
• * Alkylpolyglykolether, vorzugsweise mit 8 bis 20 Kohlenstoffatomen im Alkylrest und 8 bis 40 Ethylenoxideinheiten;
• * Alkylarylpolyglykolether, vorzugsweise mit 8 bis 20 Kohlenstoffatomen im Alkyl- bzw. Alkylarylrest und 8 bis 40 Ethylenoxideinheiten;
• * Ethylenoxid/Propylenoxid-Copolymere, vorzugsweise Blockcopolymere, günstigerweise mit 8 bis 40 Ethylenoxid- bzw. Propylenoxideinheiten.

The stabilization of the approach is carried out by means of emulsifiers and / or protective colloids. Stabilization by emulsifiers is preferred in order to obtain a low dispersion viscosity. The total amount of emulsifier is preferably 0.1 to 5 wt .-%, in particular 0.5 to 3 wt .-%, based on the total weight of the monomers A) to J). Particularly suitable emulsifiers are anionic or nonionic emulsifiers or mixtures thereof, in particular:

• * Alkyl sulfates, preferably those having 8 to 18 carbon atoms in the alkyl radical, alkyl and alkylaryl ether sulfates having 8 to 18 carbon atoms in the alkyl radical and 1 to 50 ethylene oxide units;
• * Sulfonates, preferably alkyl sulfonates having 8 to 18 carbon atoms in the alkyl radical, alkylaryl sulfonates having 8 to 18 carbon atoms in the alkyl radical, esters and half esters of sulfosuccinic acid with monohydric alcohols or alkylphenols having 4 to 15 carbon atoms in the alkyl radical; optionally, these alcohols or alkylphenols may also be ethoxylated with 1 to 40 ethylene oxide units;
• * Partial phosphoric acid esters and their alkali metal and ammonium salts, preferably alkyl and alkylaryl phosphates having 8 to 20 carbon atoms in the alkyl or alkylaryl radical and 1 to 5 ethylene oxide units;
• * Alkylpolyglykolether, preferably having 8 to 20 carbon atoms in the alkyl radical and 8 to 40 ethylene oxide units;
• * Alkylaryl polyglycol ethers, preferably having 8 to 20 carbon atoms in the alkyl or alkylaryl radical and 8 to 40 ethylene oxide units;
• * Ethylene oxide / propylene oxide copolymers, preferably block copolymers, desirably with 8 to 40 ethylene oxide or propylene oxide units.

According to the invention, preference is given to using mixtures of anionic emulsifier and nonionic emulsifier. Mixtures of an ester or half ester of sulfosuccinic acid with monohydric alcohols or alkylphenols having 4 to 15 carbon atoms in the alkyl radical as anionic emulsifier and an alkyl polyglycol ether, preferably having 8 to 20 carbon atoms in the alkyl radical and 8 to 40 ethylene oxide units, as nonionic emulsifier in a weight ratio from 8: 1 to 1: 8 very well proven.

Optionally, the emulsifiers can also be used in admixture with protective colloids. Suitable protective colloids include partially saponified polyvinyl acetates, polyvinyl pyrrolidones, carboxymethyl, methyl, hydroxyethyl, hydroxypropyl cellulose, starches, proteins, poly (meth) acrylic acid, poly (meth) acrylamide, polyvinylsulfonic acids, melamine formaldehyde sulfonates, naphthalene formaldehyde sulfonates, styrene-maleic acid and vinyl ether maleic acid copolymers. If protective colloids are used, this is preferably carried out in an amount of from 0.01 to 1.0% by weight, based on the total amount of monomers A) to I). The protective colloids can be initially charged or added before the start of the polymerization.

The initiator can be initially charged or added. Furthermore, it is also possible to submit a part of the initiator and to meter in the remainder.

The polymerization is preferably started by heating the batch to the polymerization temperature and metering in the initiator, preferably in aqueous solution. The dosages of emulsifier and monomers can be carried out separately or as a mixture. In the metered addition of mixtures of emulsifier and monomer, the procedure is such that emulsifier and monomer are premixed in a mixer upstream of the polymerization reactor. Preferably, the remainder of the emulsifier and the remainder of monomer, which were not initially charged, are metered in separately after the start of the polymerization. Preferably, the dosage is started 15 to 35 minutes after the start of the polymerization.

Furthermore, it is particularly advantageous for the purposes of the present invention that the template contains a so-called "seed latex", which is preferably obtainable by polymerization of alkyl (meth) acrylates and, moreover, desirably has a particle radius in the range from 3.0 to 20.0 nm, conveniently in the range of 5.0 to 20.0 nm. These small radii can be calculated after a defined polymerization of the seed latex, in which a shell is built up around the seed latex and the radii of the particles thus produced were measured by the Coulter method. This known in the literature method for particle size determination based on the measurement of electrical resistance, which changes in the passage of particles through a narrow measuring opening in a characteristic manner. For more details, for example Ed. Chem. Tech. Lab. 43, 553-566 (1995) be removed.

To the seed latex, the monomer components of the actual core, ie the first composition, are preferably added under conditions such that the formation of new particles is avoided. As a result, the resulting in the first stage of the process Polymerisate cup-shaped stored around the seed latex. Similarly, the monomer components of the first shell material (second composition) are added to the emulsion polymer under conditions such that the formation of new particles is avoided. As a result, the polymer formed in the second stage is stored in the form of a cup around the existing core. This procedure should be repeated for each additional shell.

According to a further preferred embodiment of the present invention, the core-shell particles according to the invention will be obtained by an emulsion polymerization process in which instead of the seed latex a long-chain aliphatic alcohol, preferably having 12 to 20 carbon atoms, is emulsified. In a preferred embodiment of this process, stearyl alcohol is used as the long chain aliphatic alcohol. The core-shell structure is obtained analogously to the procedure described above by stepwise addition and polymerization of the corresponding monomers while avoiding the formation of new particles. Further details of the polymerization process, the person skilled in the patents DE 3343766 . DE 3210891 . DE 2850105 . DE 2742178 and DE 3701579 remove.

Regardless of the specific procedure, however, it has proved to be very particularly favorable in the context of the present invention to meter in the second and the third monomer mixture in accordance with consumption.

The adjustment of the chain lengths, in particular of the (co) polymers of the second shell (third composition), can be carried out by polymerization of the monomer or of the monomer mixture in the presence of molecular weight regulators, in particular of the mercaptans known for this purpose, such as, for example, n-butylmercaptan. Dodecyl mercaptan, 2-mercaptoethanol or 2-ethylhexyl thioglycolate, pentaerythritol tetrathioglycolate; wherein the molecular weight regulators are generally used in amounts of from 0.05 to 5% by weight, based on the monomer mixture, preferably in amounts of from 0.1 to 2% by weight and more preferably in amounts of from 0.2 to 1% by weight. be used on the monomer mixture (see, for example H. Rauch-Puntigam, Th. Völker, "Acrylic and Methacrylic Compounds", Springer, Heidelberg, 1967 ; Houben-Weyl, Methods of Organic Chemistry, Vol. XIV / 1. Page 66, Georg Thieme, Heidelberg, 1961 or Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. 1, pp. 296ff, J. Wiley, New York, 1978 ). Preference is given to using n-dodecylmercaptan as molecular weight regulator.

After completion of the polymerization, residual monomer removal can be postpolymerized using known methods, for example by means of initiated postpolymerization.

Since the process according to the invention is particularly suitable for the preparation of aqueous dispersions having a high solids content greater than 50% by weight, based on the total weight of the aqueous dispersion, the relative proportions of all substances are chosen such that the total weight of components A) to J) , based on the total weight of the aqueous dispersion, greater than 50.0 wt .-%, suitably greater than 51.0 wt .-%, preferably greater than 52.0 wt .-%, is. In addition to the monomers A) to J), the substances to be considered in this context also include all other substances used, such as water, emulsifier, initiator, optionally regulators and protective colloids, etc.

Furthermore, for the purposes of the present invention, it is particularly advantageous to select the relative proportions of all components such that core-shell particles having a total radius measured by the Coulter method are in the range of 150.0 to less than 250.0 nm, preferably in the range of 170.0 to 220.0 nm.

The aqueous dispersions obtainable by the process according to the invention are characterized by a low coagulum content, which, based on the total weight of the aqueous dispersion, is preferably less than 5.0% by weight, advantageously less than 3.0% by weight, in particular less than 1.5% by weight. According to a very particularly preferred embodiment of the present invention, the aqueous dispersion, based on its total weight, less than 1.0 wt .-%, preferably less than 0.5 wt .-%, advantageously less than 0.25 wt .-% , in particular 0.10 wt .-% or less, coagulum.

The term "coagulum" in this context refers to water-insoluble constituents, which can be filtered off preferably by filtration of the dispersion expediently via a filter sleeve with clamped filter cloth no. 0.90 DIN 4188.

The core-shell particle according to the invention can be prepared from the dispersion, for example by spray drying, freeze coagulation, precipitation by addition of electrolyte or by mechanical or thermal stress, as described in US Pat DE 27 50 682 A1 or US 4,110,843 be carried out by means of a degassing extruder, are obtained. The spray-drying process is the most common, although the other processes mentioned have the merit of at least partially separating the water-soluble polymerization aids from the polymer.

The core-shell particle according to the invention serves to improve the notched impact strength of hard thermoplastics which are compatible with the hard phase, preferably of poly (meth) acrylate molding compositions, in particular of polymethyl methacrylate.

The poly (meth) acrylate molding compositions preferably contain other polymers to suitably modify the properties. These include in particular polyacrylonitriles, polystyrenes, polyethers, Polyesters, polycarbonates and polyvinyl chlorides. These polymers can be used individually or as a mixture, wherein in a very particularly preferred embodiment of the present invention, copolymers derived from the abovementioned polymers are added to the molding compositions. These include in particular styrene-acrylonitrile copolymers (SAN), which are preferably added to the molding compositions in an amount of up to 45% by weight.

Particularly preferred styrene-acrylonitrile copolymers can be obtained by the polymerization of mixtures consisting of
70.0 to 92.0 wt .-% styrene
8.0 to 30.0 wt .-% of acrylonitrile and
0.0 to 22.0 wt .-% of other comonomers, each based on the total weight of the monomers to be polymerized, exist.

In general, 10 parts to 60 parts of the impact modifier are added to 100 parts of the molding composition to be modified.

1. A) 1,0 bis 50,0 Gew.-% mindestens eines Kern-Schale-Teilchens gemäß mindestens einem der Ansprüche 1 bis 9;
2. B) 1,0 bis 99,0 Gew.-% mindestens eines (Meth)acrylpolymers,
3. C) 0,0 bis 45 Gew.-%, vorzugsweise 1,0 bis 45 Gew.-%, Styrol-Acrylnitril-Copolymere und
4. D)0,0 bis 10,0 Gew.-% weiterer Zusatzstoffe

wobei sich die Gewichtsprozente zu 100,0 Gew.-% addieren.Particularly preferred molding composition according to the invention, in each case based on their total weight ,:

1. A) 1.0 to 50.0 wt .-% of at least one core-shell particle according to at least one of claims 1 to 9;
2. B) 1.0 to 99.0% by weight of at least one (meth) acrylic polymer,
3. C) 0.0 to 45 wt .-%, preferably 1.0 to 45 wt .-%, styrene-acrylonitrile copolymers and
4. D) 0.0 to 10.0 wt .-% of other additives

wherein the weight percent add up to 100.0 wt .-%.

1. a) 50,0 bis 100,0 Gew.-%, zweckmäßigerweise 60,0 bis 100,0 Gew.-%, besonders bevorzugt 75,0 bis 100,0 Gew.-%, insbesondere 85,0 bis 99,5 Gew.-%, Alkylmethacrylat-Wiederholungseinheiten mit 1 bis 20, vorzugsweise 1 bis 12, zweckmäßigerweise 1 bis 8, insbesondere 1 bis 4, Kohlenstoffatomen im Alkylrest,
2. b) 0,0 bis 40,0 Gew.-%, vorzugsweise 0,0 bis 25,0 Gew.-%, insbesondere 0,1 bis 15,0 Gew.- %, Alkylacrylat-Wiederholungseinheiten mit 1 bis 20, vorzugsweise 1 bis 12, zweckmäßigerweise 1 bis 8, insbesondere 1 bis 4, Kohlenstoffatomen im Alkylrest und
3. c) 0,0 bis 8,0 Gew.-% styrolische Wiederholungseinheiten der allgemeinen Formel (I),

wobei sich die Gewichtsprozente zu 100,0 Gew.-% addieren.In this case, the (meth) acrylic polymer, in each case based on its total weight, preferably comprises

1. a) 50.0 to 100.0 wt .-%, suitably 60.0 to 100.0 wt .-%, particularly preferably 75.0 to 100.0 wt .-%, in particular 85.0 to 99.5 wt %, Alkyl methacrylate repeat units from 1 to 20, preferably 1 to 12, suitably 1 to 8, in particular 1 to 4, carbon atoms in the alkyl radical,
2. b) from 0.0 to 40.0% by weight, preferably from 0.0 to 25.0% by weight, in particular from 0.1 to 15.0% by weight, of alkyl acrylate repeat units having from 1 to 20, preferably 1 to 12, suitably 1 to 8, in particular 1 to 4, carbon atoms in the alkyl radical and
3. c) from 0.0 to 8.0% by weight of styrenic repeat units of the general formula (I),

wherein the weight percent add up to 100.0 wt .-%.

According to a particularly preferred embodiment of the present invention, the (meth) acrylic polymer contains, based on its total weight, at least 50.0% by weight, expediently at least 60.0% by weight, preferably at least 75.0% by weight, in particular at least 85.0% by weight of methyl methacrylate repeat units. _

Further, the (meth) acrylic polymer preferably has a number average molecular weight in the range of 1,000 to 100,000,000 g / mol, preferably in the range of 10,000 to 1,000,000 g / mol, especially in the range of 50,000 to 500,000 g / mol. In this case, the molecular weight, for example by gel permeation chromatography under calibration on polystyrene can be determined.

Such mixtures can be prepared in various ways. For example, it is possible to mix the dispersion of the core-shell particle with an aqueous dispersion of the mixing component and to coagulate the mixture, to separate the aqueous phase and to melt the coagulum into a molding compound. In this method, a particularly uniform mixing of the two masses can be achieved. The components can also be prepared separately and isolated and mixed in the form of their melts or as powders or granules and homogenized in a multi-screw extruder or on a roll mill.

Usual additives can be mixed in any suitable processing stage. These include u. a. Dyes, pigments, fillers, reinforcing fibers, lubricants, UV protectants, etc.

Within the scope of a very particularly preferred embodiment of the present invention, the molding composition, based in each case on its total weight, contains 0.1 to 10% by weight, preferably 0.5 to 5.0% by weight, in particular 1.0 to 4, 0 wt .-%, of a further polymer (AP), which in comparison with the (meth) acrylic polymer by at least 10%, preferably at least 50%, in particular at least 100% higher weight average molecular weight. In this case, the molecular weight, for example by gel permeation chromatography under calibration on polystyrene can be determined.

1. a) 50,0 bis 100,0 Gew.-%, zweckmäßigerweise 60,0 bis 100,0 Gew.-%, besonders bevorzugt 75,0 bis 100,0 Gew.-%, insbesondere 85,0 bis 99,5 Gew.-%, Alkylmethacrylat-Wiederholungseinheiten mit 1 bis 20, vorzugsweise 1 bis 12, zweckmäßigerweise 1 bis 8, insbesondere 1 bis 4, Kohlenstoffatomen im Alkylrest,
2. b) 0,0 bis 40,0 Gew.-%, vorzugsweise 0,0 bis 25,0 Gew.-%, insbesondere 0,1 bis 15,0 Gew.- %, Alkylacrylat-Wiederholungseinheiten mit 1 bis 20, vorzugsweise 1 bis 12, zweckmäßigerweise 1 bis 8, insbesondere 1 bis 4, Kohlenstoffatomen im Alkylrest und
3. c) 0,0 bis 8,0 Gew.-% styrolische Wiederholungseinheiten der allgemeinen _ Formel (I),

wobei sich die Gewichtsprozente zu 100,0 Gew.-% addieren.Polymers (AP) which are particularly suitable according to the invention comprise, in each case based on their total weight, preferably

1. a) 50.0 to 100.0 wt .-%, suitably 60.0 to 100.0 wt .-%, particularly preferably 75.0 to 100.0 wt .-%, in particular 85.0 to 99.5 wt %, Alkyl methacrylate repeat units having 1 to 20, preferably 1 to 12, suitably 1 to 8, in particular 1 to 4, carbon atoms in the alkyl radical,
2. b) from 0.0 to 40.0% by weight, preferably from 0.0 to 25.0% by weight, in particular from 0.1 to 15.0% by weight, of alkyl acrylate repeat units having from 1 to 20, preferably 1 to 12, suitably 1 to 8, in particular 1 to 4, carbon atoms in the alkyl radical and
3. c) from 0.0 to 8.0% by weight of styrenic repeat units of the general formula (I),

wherein the weight percent add up to 100.0 wt .-%.

According to a particularly preferred embodiment of the present invention, the polymer (AP), based on its total weight, at least 50.0 wt .-%, advantageously at least 60.0 wt .-%, preferably at least 75.0 wt .-%, in particular at least 85.0% by weight of methyl methacrylate repeat units.

Furthermore, the polymer (AP) preferably has a weight-average molecular weight in the range from 10,000 to 100,000,000 g / mol, preferably in the range from 50,000 to 5,000,000 g / mol, advantageously in the range from 100,000 to 1,000,000 g / mol, in particular in the range of 250,000 to 600,000 g / mol. In this case, the molecular weight, for example by gel permeation chromatography under calibration on polystyrene can be determined.

Blends of the core-shell particles, in particular with polymethyl methacrylate, are particularly suitable for the production of moldings, expediently with a wall thickness over 1 mm, such as extruded sheets of 1 to 10 mm thickness, which can be punched well and, for example, for the production of printable panels for Appliances are useful, or for the production of molded molded articles of high quality, eg. B. vehicle windows. Thinner films, for example, 50 microns thick can also be made from it.

• * vorzugsweise durch eine Vicat-Erweichungstemperatur nach ISO 306 (B50) von mindestens 85 °C, bevorzugt von mindestens 90 °C und besonders bevorzugt von mindestens 93 °C,
• * vorzugsweise durch eine Kerbschlagzähigkeit nach Charpy (ISO 179) bei 23 °C von mindestens 6,0 kJ/m², und vorzugsweise von mindestens 2,5 kJ/m², insbesondere von mindestens 2,5 kJ/m², bei -10 °C und
• * vorzugsweise durch einen E-Modul nach ISO 527-2 von mindestens 1500 MPa
• * vorzugsweise durch einen Haze nach ASTM D 1003 (1997) von vorzugsweise maximal 2,5 %,
• * vorzugsweise durch eine Schmelzviskosität nach DIN 54811 (1984) größer 2000 Pa s und günstigerweise kleiner 4500 Pa s,
• * vorzugsweise durch eine Transmission (D 65/10°) nach DIN 5033/5036 von mindestens 88,5 % sowie
• * vorzugsweise durch eine Strangaufweitung nach DIN 54811 (1984) im Bereich von 0 bis 20 %

aus.The molded articles obtainable according to the invention are distinguished

• preferably by a Vicat softening temperature according to ISO 306 (B50) of at least 85 ° C, preferably of at least 90 ° C and more preferably of at least 93 ° C,
• preferably by a Charpy impact strength (ISO 179) at 23 ° C of at least 6.0 kJ / m ² , and preferably of at least 2.5 kJ / m ² , in particular of at least 2.5 kJ / m ² , 10 ° C and
• * preferably by an E-module according to ISO 527-2 of at least 1500 MPa
• preferably by haze according to ASTM D 1003 (1997) of preferably not more than 2.5%,
• preferably by a melt viscosity according to DIN 54811 (1984) greater than 2000 Pa s and favorably less than 4500 Pa s,
• * preferably by a transmission (D 65/10 °) according to DIN 5033/5036 of at least 88.5% as well as
• * preferably by a strand expansion according to DIN 54811 (1984) in the range of 0 to 20%

out.

In the context of a particularly preferred embodiment of the present invention, the moldings according to the invention are used as a mirror housing or spoiler of a vehicle, as a pipe, as a cover or as a component of a refrigerator.

The following examples and comparative examples serve to illustrate the present invention, without this being intended to limit the scope of the invention.

I. Core-shell particles A. Preparation of the seed latex

A seed latex was prepared by emulsion polymerization of a monomer composition containing 98% by weight of ethyl acrylate and 2% by weight of allyl methacrylate. These particles, about 20 nm in diameter, were about 10% by weight in water.

B. Preparation of the core-shell particles

The synthesis of the core-shell particles described below was carried out according to preparation process A (inventive examples B1 and B2), B (comparative examples VB1 and VB2), C (comparative examples VB3 and VB4 according to FIGS US 3,793,402 ) or D (Comparative Examples VB5, VB6 and VB7 according to DE 41 36 993 ). In this case, the emulsions I to III specified in Table 1 were used.

B.1 Production Method A (Inventive Examples)

At 83 ° C (internal temperature boiler) 19.416 kg of water were placed in a polymerization with stirring. There was an addition of 16.2 g of sodium carbonate and 73 g of seed latex. Subsequently, the emulsion I was added over 1 h. 10 minutes after the end of the emulsion I emulsion II was added over a period of about 2 h. Subsequently, about 90 minutes after the end of the emulsion II emulsion III was added over a period of about 1 h. 30 min after the end of the emulsion III was cooled to 30 ° C.

To separate the core-shell particles, the dispersion was frozen for 2 d at -20 ° C, then thawed again and the coagulated dispersion separated on a filter cloth. The drying of the solid was carried out at 50 ° C in a drying oven (duration: about 3 d). Further details can be found in Table 1.

The particle size of the core-shell particles (see Table 2) was determined with the aid of a Coulter N4 apparatus, the particles being measured in dispersion.

B.2 Production Method B (Comparative Examples VB1 and VB2)

At 52 ° C. (internal temperature of the vessel) 20.129 kg of water were placed in a polymerization kettle with stirring and 1.18 g of acetic acid, 0.04 g of iron (II) sulfate, 12.9 g of sodium disulfite and 121.5 g of seed latex were added , Subsequently, the emulsion I was added over 1.5 h. 10 minutes after the end of the emulsion I, 38.8 g of sodium disulfite dissolved in 1176 g of water was added and the emulsion II was added over a period of about 2.5 h. Subsequently, about 30 minutes after the end of the emulsion II, 12.9 g of sodium disulfite dissolved in 588.2 g of water were added and the emulsion III was added over a period of about 1.5 h. 30 min after the end of the emulsion III was cooled to 30 ° C and adjusted with sodium carbonate to pH = 8. A higher solids content of the resulting dispersion than 48 wt .-% could not be achieved, since otherwise an increased amount of coagulum was observed (> 1 wt .-% of the dispersion).

To separate the core-shell particles, the dispersion was frozen for 2 d at -20 ° C, then thawed again and the coagulated dispersion separated on a filter cloth. The drying of the solid was carried out at 50 ° C in a drying oven (duration: about 3 d). Further details can be found in Table 1.

The particle size of the core-shell particles (see Table 2) was determined with the aid of a Coulter N4 apparatus, the particles being measured in dispersion.

B.3 Preparation method C (Comparative Examples according to US 3,793,402 )

The preparation of Comparative Examples VB3 and VB4 was carried out essentially analogously to Example 1 US 3,793,402 , Only the monomer ratio of the first shell was adapted to that of the examples according to the invention and the dispersions were prepared by means of a "triple batch", ie the monomers for the core, the first and the second shell were added at once and then polymerized. Further details of the synthesis are shown in Tables 3 to 6. The resulting solids and Koagulatgehalte are summarized in Table 7. In order to determine the coagulum content, the entire dispersion was filtered through a VA filter sleeve with clamped screen cloth No. 0.90 DIN 4188. The resulting residue was rinsed with water until clear. If coagulum occurred, it was pressed out with a spatula, placed in a previously tared beaker and weighed with a laboratory balance to 0.1 g. The filtrate was also weighed to 1 gram with the laboratory balance. The mass of the total dispersion is calculated from the mass of coagulum and the mass of filtrate. $$\mathrm{coagulate}\left(\mathrm{weight}\mathrm{,}\mathrm{-}\mathrm{\%}\right)\mathrm{=}\mathrm{100}\mathrm{\times }\left[\mathrm{Mass\; of\; accumulating\; coagulum}\left(\mathrm{G}\right)\right]\mathrm{/}\left[\mathrm{Mass\; of\; the\; total\; dispersion}\left(\mathrm{G}\right)\right]$$

• R10, R50, R90: Radius unterhalb dem 10, 50 bzw. 90 Gew.-% der Kern-Schale-Teilchen in der Dispersion zu finden sind $$\mathrm{U}\mathrm{80}\mathrm{:}\mathrm{=}\left(\mathrm{R}\mathrm{90}\mathrm{-}\mathrm{R}\mathrm{10}\right)\mathrm{/}\mathrm{R}\mathrm{50}\left(\mathrm{Maß\; f}\ddot{\mathrm{u}}\mathrm{r\; Einheitlichkeit\; der\; TGV}\mathrm{-}\mathrm{deckt}\mathrm{80}\mathrm{Gew}\mathrm{.}\mathrm{-}\mathrm{\%}\mathrm{der\; Kern}\mathrm{-}\mathrm{Schale}\mathrm{-}\mathrm{Teilchen\; ab}\right)$$
  
• B.4 Herstellungsverfahren D (Vergleichsbeispiele gemäß DE 41 36 993 )

The radii of the resulting core-shell particles and their particle size distribution are given in Table 8. This was done in this case the characterization of the particle size both by means of a Coulter N4 instrument as well as by means of an analytical ultracentrifuge. In addition, the particle size distribution (TGV) is determined by means of the analytical ultracentrifuge. The sizes given in Table 8 are defined as follows:

• R10, R50, R90: radius are found below the 10, 50 and 90 wt .-% of the core-shell particles in the dispersion $$\mathrm{U}\mathrm{80}\mathrm{:}\mathrm{=}\left(\mathrm{R}\mathrm{90}\mathrm{-}\mathrm{R}\mathrm{10}\right)\mathrm{/}\mathrm{R}\mathrm{50}\left(\mathrm{Measure\; f}\ddot{\mathrm{u}}\mathrm{r\; Uniformity\; of\; TGV}\mathrm{-}\mathrm{covers}\mathrm{80}\mathrm{weight}\mathrm{,}\mathrm{-}\mathrm{\%}\mathrm{the\; core}\mathrm{-}\mathrm{Bowl}\mathrm{-}\mathrm{Particles\; off}\right)$$
  
• B.4 Preparation Method D (Comparative Examples According to DE 41 36 993 )

The preparation of Comparative Examples VB5, VB6 and VB7 was carried out essentially according to Example 1 DE 41 36 993 , However, the initial emulsion amount was reduced from 30% to 20% by weight to adjust the particle size of the dispersions to those of the examples of the present invention. Furthermore, an aqueous initiator solution was added in the last stage. Further details of the synthesis are shown in Tables 3 to 6, the characteristic characteristics are summarized in Tables 7 and 8 and compared with the polymer B1.

C. Preparation of a mixing dispersion

The blending dispersion (solids content about 50% by weight) is prepared by emulsion polymerization and has the monomer composition of 95% by weight of methyl methacrylate and 5% by weight of ethyl acrylate. The particle size of the particles is 260 nm in diameter (measured in the Coulter N4 - determination device) and the J value of the polymer (measure of the molecular weight) is 203 mL / g (measured in chloroform at a temperature of 25 ° C, DIN ISO 1628-6)

II. Molding compounds A. Blending of the molding compositions

A molding composition based on polymethyl methacrylate, PLEXIGLAS ^® 7 N (Fa. Röhm GmbH & Co. KG, Darmstadt) was mixed with the respective core-shell particles by means of the extruder.

B. Testing of the molding compositions

• Schmelzviskosität ηs (220 °C/5 MPa): DIN 54811 (1984)
• Strangaufweitung B: DIN 54811 (1984)
• Vicat-Erweichungstemperatur (16 h/80 °C): DIN 1S0 306 (Aug. 1994)
• Izod - Kerbschlagzähigkeit: ISO 180 (1993)
• Charpy - Kerbschlagzähigkeit: ISO 179 (1993)
• E-Modul: ISO 527-2
• Transmission (D 65/10°): DIN 5033/5036
• Haze (Hazemeter BYK Gardner Hazegard-plus): ASTM D 1003 (1997)

Test specimens were prepared from the blended molding compositions. The molding compositions or the corresponding test specimens were tested according to the following measurement methods:

• Melt viscosity ηs (220 ° C / 5 MPa): DIN 54811 (1984)
• Strand expansion B: DIN 54811 (1984)
• Vicat softening temperature (16 h / 80 ° C): DIN 1S0 306 (Aug. 1994)
• Izod - notched impact strength: ISO 180 (1993)
• Charpy Impact Strength: ISO 179 (1993)
• Modulus of elasticity: ISO 527-2
• Transmission (D 65/10 °): DIN 5033/5036
• Haze (Hazemeter BYK Gardner Hazegard-plus): ASTM D 1003 (1997)

The results of the tests are also shown in Table 2.

It clearly recognizes the advantages of the blends A, B, C and D according to the invention over the conventionally impact-modified molding compositions (VB A and VB B):

At a comparable content of the core-shell particles (<40 wt .-%) is the notched impact strength Charpy of the molding compositions according to the invention at 23 ° C significantly higher than that of the comparative molding compounds and at -10 ° C at a comparable level. Table 2: Test results of the impact-modified molding compositions mixdown VB A VB B A B C D ^* Core-shell particles VB1 VB2 B1 B1 B2 B2 Particle radius [nm] 188 188 164 164 Content of core-shell particles in Plexiglas ^® 7N [wt .-%] 39.3 39.3 38.4 35.7 38.4 38.4 Viscosity ηs [Pa s] 2120 2780 3210 3060 3210 3600 Strand expansion B [%] 21.4 11.0 3.8 6.9 5.6 12.6 Vicat softening temperature [° C] 99.8 95.5 95.6 96.2 94.9 95 Izod - notched impact strength 23 ° C: [kJ / m ² ] 6.2 6.1 6.4 6.0 -10 ° C: [kJ / m ² ] 4.1 3.5 3.6 3.7 Charpy - notched impact strength 23 ° C: [kJ / m ² ] 5.2 6.0 7.4 6.7 -10 ° C: [kJ / m ² ] 2.0 2.9 3.9 2.7 Modulus of elasticity [MPa] 2180 1805 1660 1900 Transmission [%] 89.1 88.7 90.5 90.7 90.9 Haze 23 ° C [%] 1.2 1.3 2.3 2.0 1.8 1.6 40 ° C [%] 5.43 5.39 5.8 5.8 4.7 4.7 ^* with mixing dispersion (3% by weight of the solid in the

Mixed dispersion based on the solid in the dispersion) Table 3: Structure of the core-shell particles VB3 VB4 VB5 VB6 VB7 B1 core 25.05 25.05 20 20 20 35 1st shell 50.5 50.5 50 50 50 45 2nd shell 25 25 30 30 30 20 VB3 VB4 VB5 VB6 VB7 B1 methyl methacrylate 99.8 99.8 98.6 98.6 98.6 95.8 methyl acrylate 0.87 0.87 0.87 ethyl acrylate 4.0 allyl methacrylate 0.2 0.2 0.52 0.52 0.52 0.2 VB3 VB4 VB5 VB6 VB7 B1 butyl acrylate 81.1 81.1 80.1 80.1 80.1 81.0 styrene 17.9 17.9 18.9 18.9 18.9 18.1 allyl methacrylate 1.0 1.0 1.0 1.0 1.0 0.9 VB3 VB 4 VB5 VB6 VB7 B1 methyl methacrylate 96.0 96, 0 96 96 96 90 ethyl acrylate 4.0 4.0 4 4 4 10 dodecyl VB3 VB4 VB5 VB6 VB7 B1 Solid content ⁺ [% by weight] 46.3 53 50.2 50.2 53 53 Coagulum content ⁺ [% by weight] 0.2 > 25 0.12 0.16 20 0.1 ^{+ in} each case based on the total weight of the dispersion VB3 VB4 VB5 VB6 VB7 B1 R10 ¹ [nm] 172 113 133 165 R50 ¹ [nm] 163 123 145 180 R90 ¹ [nm] 166 145 168 202 U80 ¹ 0.08 0.26 0.25 0.21 Particle radius ² [nm] 191 128 162 188 Particle radius ^{2 of} the 59 64 10 Seed latices or polymerized Initial emulsion [nm] ¹ ultracentrifuge
² measured with Coulter N4

Claims (17)

1. Process for preparing an aqueous dispersion, by

   a) using water and emulsifier to form an initial charge,

   b) adding from 25.0 to 45.0 parts by weight of a first composition
   comprising

   A) from 50.0 to 99.9 parts by weight of alkyl methacrylates having from 1 to 20 carbon atoms in the alkyl radical,

   B) from 0.0 to 40.0 parts by weight of alkyl acrylates having from 1 to 20 carbon atoms in the alkyl radical,

   C) from 0.1 to 10.0 parts by weight of crosslinking monomers and

   D) from 0.0 to 8.0 parts by weight of styrenic monomers of the general formula (I)

   

   where each of the radicals R¹ to R⁵, independently of the others, is hydrogen, a halogen, a C_1-6-alkyl group or a C_2-6-alkenyl group, and the radical R⁶ is hydrogen or an alkyl group having from 1 to 6 carbon atoms,

   and polymerizing to a conversion of at least 85.0% by weight, based on the total weight of components A), B), C) and D),

   c) adding from 35.0 to 55.0 parts by weight of a second composition comprising

   E) from 80.0 to 100.0 parts by weight of (meth)acrylates

   F) from 0.05 to 10.0 parts by weight of crosslinking monomers and

   G) from 0.0 to 20.0 parts by weight of styrenic monomers of the general formula (I),
   and polymerizing to a conversion of at least 85.0% by weight, based on the total weight of components E), F) and G),

   d) adding from 10.0 to 30.0 parts by weight of a third composition comprising

   H) from 50.0 to 100.0 parts by weight of alkyl methacrylates having from 1 to 20 carbon atoms in the alkyl radical,

   I) from 0.0 to 40.0 parts by weight of alkyl acrylates having from 1 to 20 carbon atoms in the alkyl radical and

   J) from 0.0 to 10.0 parts by weight of styrenic monomers of the general formula (I)
   and polymerizing to a conversion of at least 85.0% by weight, based on the total weight of components H), I) and J),

   where the parts by weight given for the compositions b), c) and d) give a total of 100.0 parts by weight,
   characterized in that

   e) each polymerization is carried out at a temperature in the range from above 60 to below 90°C and

   f) the relative proportions of all of the substances are selected in such a way that the total weight of components A) to J), based on the total weight of the aqueous dispersion, is greater than 50.0% by weight.
2. Process according to Claim 1, characterized in that an aqueous dispersion is prepared which comprises less than 5.0% by weight of coagulate, based on its total weight.
3. Process according to Claim 1 or 2, characterized in that 90.00 to 99.99 parts by weight of water and from 0.01 to 10.00 parts by weight of emulsifier are used to form an initial charge, where the parts by weight given give a total of 100.00 parts by weight.
4. Process according to at least one of the preceding claims, characterized in that use is made of an anionic or non-ionic emulsifiers.
5. Process according to at least one of the preceding claims, characterized in that an aqueous emulsion which comprises a seed latex is used to form an initial charge.
6. Process according to Claim 5, characterized in that a seed latex whose particle radius, measured by the Coulter method, is in the range from 5.0 to 20.0 nm is used to form an initial charge.
7. Process according to at least one of the preceding claims, characterized in that an aqueous emulsion which comprises an alkyl alcohol having from 12 to 20 carbon atoms in the alkyl radical is used to form an initial charge.
8. Process according to at least one of the preceding claims, characterized in that the polymerization in steps b) to d) is initiated using a peroxodisulphate, preferably using ammonium and/or alkali metal peroxodisulphate.
9. Process according to at least one of the preceding claims, characterized in that the relative proportions of all of the substances are selected in such a way that core-shell particles are obtained with an overall radius, measured by the Coulter method, in the range from 150.0 to less than 250.0 nm.
10. Process according to at least one of the preceding claims, characterized in that the second and the third monomer mixture are metered in as required by consumption.
11. Core-shell particles obtainable by a process according to at least one of the preceding claims, in particular according to Claim 6.
12. Moulding composition comprising, based in each case on its total weight:

    A) from 1.0 to 50.0% by weight of at least one core-shell particle according to Claim 11;

    B) from 1.0 to 99.0% by weight of at least one (meth)acrylic polymer,

    C) from 0.0 to 45% by weight of styrene-acrylonitrile polymers, and

    D) from 0.0 to 10.0% by weight of other additives

    where the percentages by weight give 100.0% by weight in total.
13. Moulding composition according to Claim 12, characterized in that the (meth)acrylic) [sic] polymer encompasses, based in each case on its total weight,

    a) from 50.0 to 100.0% by weight of alkyl methacrylate repeat units having from 1 to 20 carbon atoms in the alkyl radical,

    b) from 0.0 to 40.0% by weight of alkyl acrylate repeat units having from 1 to 20 carbon atoms in the alkyl radical and

    c) from 0.0 to 8.0% by weight of styrenic repeat units of the general formula (I),

    where the percentages by weight give 100.0% by weight in total.
14. Moulding composition according to Claim 12 or 13, characterized in that the moulding composition comprises styrene-acrylonitrile copolymers, where the styrene-acrylonitrile copolymers were obtained by polymerizing any mixture which is composed of from 70 to 92% by weight of styrene from 8 to 30% by weight of acrylonitrile and from 0 to 22% by weight of other comonomers, based in each case on the total weight of the monomers to be polymerized.
15. Moulding composition according to at least one of Claims 12 to 14, characterized in that it comprises, based on its total weight, from 0.1 to 10.0% by weight of another polymer whose weight-average molecular weight is higher by at least 10% than that of the (meth)acrylic polymer b).
16. Moulding obtainable from a moulding composition according to at least one of Claims 12 to 15.
17. Moulding according to Claim 16, characterized in that the moulding has a Vicat softening point ISO 306 (B50) of at least 85, preferably at least 90 and particular preferably at least 93°C, a notched impact strength NIS (Charpy 179/1eA) to ISO 179 of at least 6.0 kJ/m² at 23°C and of at least 2.5 kJ/m² at -10 °C, a modulus of elasticity to ISO 527-2 of at least 1500 Pa s, a haze to ASTM D 1003 (1997) of at most 2.5%, a transmittance (D 65/10°) to DIN 5033/5036 of at least 88.5%.